1. Field of the Invention
The present invention relates to a high-resolution two-dimensional (2D)-three-dimensional (3D) switchable autostereoscopic display apparatus, and more particularly, to a high-resolution 2D-3D switchable autostereoscopic display apparatus that provides the full resolution of a display panel and without crosstalk.
2. Description of the Related Art
A 3D display apparatus produces a left eye image and a right eye image having a binocular parallax and separately directs the left and right eye images to a left eye and a right eye, respectively. The user recognizes the left eye image and the right eye image provided by the 3D display apparatus through the retina of the corresponding eyes and thus can see a stereoscopic 3D image. Generally, 3D display apparatuses can be roughly classified into a parallax barrier type 3D display apparatus and a lenticular type 3D display apparatus.
In the parallax barrier 3D display apparatuses, a left eye image and a right eye image are displayed on alternating vertical columns of pixels and separated through a very thin vertical lattice, that is, a barrier. The left eye image in a vertical column and the right eye image in a vertical column are separated by the barrier, so that the left and right eyes respectively receive images of different view points to thereby see a 3D image. Referring to FIG. 1, a lenticular type 3D display apparatus 10 generally includes a display panel 11 including left and right pixels L and R that are alternately arranged to display a right eye image and a left eye image, respectively, and a lenticular lens sheet 12 installed in front of the display panel 11 to separate the viewing zones of the left eye image and the right eye image.
In a conventional 3D image display apparatus as described above, the left eye image and the right eye image are displayed at the same time on a single display panel, and thus the resolution of the 3D image seen by the user is half of the resolution of the display panel. Moreover, a complicated structure is required to be able to switch between a 2D image mode and a 3D image mode.
Accordingly, a 3D image display apparatus which can provide a 3D image without a reduction in resolution using a fast response liquid crystal display (LCD) having a refresh rate of 120 Hz is being developed.
For example, Japanese Patent Laid-Open Gazette No. 2004-325494 discloses a 3D image display apparatus that has a display panel, an image separation unit, and a light deflecting unit. The display panel periodically shifts the right and left images alternately displayed, on a pixel-by-pixel basis. The conventional image separation unit, such as a parallax barrier, is placed in front of the display panel and separates the right and left images that are alternately displayed on the display panel. At this point, the light deflecting unit is shifted in synchronization with the shift period of the right and left images of the display panel, and thus deflects the left eye image to the left eye and the right eye image to the right eye. In the above-described configuration, a user can barely notice the reduction in the resolution because the locations of the display panel at which the left eye image and the right eye image are displayed are switched at high speed. However, the light deflecting unit is formed of a ferroelectric liquid crystal, which is expensive, and light loss due to the parallax barrier is great.
FIG. 2 is a schematic view of a related art 2D-3D switchable autostereoscopic display apparatus 20, which is disclosed in U.S. Pat. No. 5,969,850. Referring to FIG. 2, the 3D image display apparatus 20 includes a backlight unit 21, a spatial light modulator 22, a lenticular lens sheet 23, and a fast response LCD panel 26. The spatial light modulator 22 includes a plurality of cells 24 and 25, which are switched between a transparent state and an opaque state according to the ON/OFF state of the power supplied thereto. The LCD panel 26 alternately displays the left eye image and the right eye image on the entire screen at a fast refresh rate. The spatial light modulator 22 is synchronized with the switching time of the left and right eye images of the LCD panel 26 to switch the cells 24 and 25 into the transparent or opaque state. For example, while the LCD panel 26 is displaying a left eye image, the spatial light modulator 22 switches the left eye cell 24 to a transparent state, and thus the light emitted from the backlight unit 21 heads only to the left eye viewing zone 28 of the user. While the LCD panel 26 is displaying a right eye image, the spatial light modulator 22 switches on the right eye cell 25 so that the light emitted from the backlight unit 21 heads only to the right eye viewing zone 27 of the user. In a general 2D mode, all of the cells 24 and 25 of the spatial light modulator 22 are turned on.
However, in U.S. Pat. No. 5,969,850, expensive ferroelectric liquid crystal must be also used to provide a spatial light modulator which can be switched at high speed. Moreover, in U.S. Pat. No. 5,969,850, crosstalk occurs between a left eye image and a right eye image for the following reasons, and thus the user cannot watch an accurate 3D image.
In general, most display panels scan a frame from top to bottom. Thus, while a previous frame is being displayed at the bottom of the screen, the next frame is displayed at the top of the screen. As illustrated in FIG. 3, a right eye image is displayed on the entire screen at time 0, and a left eye image is displayed on the entire screen at time T, where T is the time required to completely scan one frame. However, since the right eye image is continually changing to the left eye image between time 0 and time T, the left eye image is displayed at the top of the screen and at the same time the right eye image is displayed at the bottom of the screen. As a result, there exists a period when the left eye image and the right eye image share the screen. Therefore, as in U.S. Pat. No. 5,969,850, when the cells 24 and 25 of the spatial light modulator 22 are simply alternately turned on and off, the left eye image and the right eye image may not be completely separated and sensed by the left eye and the right eye of the user at the same time.